﻿// ===================================
// <copyright>LogoUI Co.</copyright>
// <author>Vlad Spivak</author>
// <email>mailto:vlads@logoui.co.il</email>
// <created>20/00/10</created>
// <lastedit>20/00/10</lastedit>

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the 'Software'), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//
// <remarks>Part of this software based on various internet sources, mostly on the works
// of members of Wpf Disciples group http://wpfdisciples.wordpress.com/
// Also project may contain code from the frameworks: 
//        Nito 
//        OpenLightGroup
//        nRoute
// </remarks>
// ====================================================================================//


using System;

namespace LogoUI.ViewModels
{
  /// <summary>
  /// Represents a semaphore for locking user interface updating.
  /// </summary>
  internal class ReentranceGuard
  {
    /// <summary>
    /// Represents an automatic reference counter for <see cref="ReentranceGuard"/> class.
    /// </summary>
    class Raiser : IDisposable
    {
      ///////////////////////////////////////////////////////////////////
      // Private members
      private readonly ReentranceGuard _reentranceGuard;
      /// <summary>
      /// Initializes a new instance of the <see cref="Raiser"/> class.
      /// </summary>
      /// <param name="owner">The owner of the instance.</param>
      public Raiser(ReentranceGuard owner)
      {
        _reentranceGuard = owner;
        _reentranceGuard.m_counter++;
      }
      /// <summary>
      /// Disposes locked application resources.
      /// </summary>
      public void Dispose()
      {
        _reentranceGuard.m_counter--;
      }
    }

    ///////////////////////////////////////////////////////////////////
    // Private members
    private int m_counter = -1;

    ///////////////////////////////////////////////////////////////////
    // Private members
    /// <summary>
    /// Gets automatic reference counter.
    /// </summary>
    public int Counter
    {
      get { return m_counter; }
    }
    /// <summary>
    /// Gets user interface lock flag based on the <see cref="Counter"/> value.
    /// </summary>
    public bool IsLocked
    {
      get { return this.Counter > 0; }
    }
    ///////////////////////////////////////////////////////////////////
    // Private members
    /// <summary>
    /// Increments the counter of the references.
    /// </summary>
    /// <returns>The object, which decrements the reference on its disposure.</returns>
    public IDisposable Raise()
    {
      return new Raiser(this);
    }
  }
}
